1. Field of the Invention
The present invention relates to a busbar module and a battery pack.
2. Description of the Related Art
<Battery Module for Use in Electric Vehicles or Hybrid Vehicles>
In order to increase the output of a battery module for use in electric vehicles or hybrid vehicles, battery cells are disposed in a state of being overlapped with each other such that electrode terminals on one side of the battery cells are arranged in a row and electrode terminals on the other side thereof are arranged in a row. Then, the battery module is configured in such a manner that the electrode terminals of the adjacent battery cells are connected to each other by busbars and thus a large number of battery cells are connected to each other in series or in parallel.
<Drawbacks of the Battery Module in which a Large Number of Battery Cells are Arranged>
However, assembly tolerances are set between the plurality of battery cells that are overlapped with each other. For this reason, in the battery module in which a number of battery cells are arranged, there is a case where pitches between the electrode terminals formed in the adjacent battery cells are shifted by accumulation of the tolerances. In the battery module, furthermore, a temperature rises during use of the battery cells to cause expansion or shrinkage of the battery cells in an arrangement direction, and thus the pitches between the electrode terminals may be shifted. When the pitches between the electrode terminals were larger shifted, there was a concern that a positional shift could not be absorbed in a conventional integrally-molded connection plate. In the following description, it is referred to as a tolerance including the tolerance and errors caused by the temperature rising.
<Battery Module Capable of Adjusting the Pitch Shift>
A battery module for eliminating such a pitch shift is disclosed in which the shift of pitches between adjacent electrode terminals can be easily adjusted (see Japanese Patent Application Laid-open No. 2011-210710). In the battery module disclosed in Japanese Patent Application Laid-open No. 2011-210710, portions of a flat cable to be disposed between adjacent busbars are provided with folded portions formed by folding the flat cable at folded wires intersecting with a longitudinal direction of the flat cable, and the pitches are allowed to absorb in the folded portions.
The battery cells are used much more to largely increase the output of the battery pack, and thus the number of voltage detecting wires also more increases. In that case, according to the battery module disclosed in Japanese Patent Application Laid-open No. 2011-210710, the breadth (direction perpendicular to the longitudinal direction) of the flat cable becomes longer, and thus the dimension of the battery pack increases, resulting in being contrary to the needs of the times which aims for downsizing.